rubber isolation washers

tubes4hifi wrote:aren't you guys still having transformer contact the chassis when using these thin rubber washers?I use 1/8" sorbothane under the transformers, and then use the neoprene washers.Sometimes easier to find (or maybe the same) are fiber (fibre) washers, made of a semi-hard material, like dense cardboard,usually easy to find in any hardware store. Lots of sorbothane on ebay.Cut one of these in 4 pieces for your transformers http://www.ebay.com/itm/Sorbothane-SHEET-6X6x1-8IN-VIBRATION-ISOLATION-RUBBER-PAD-150MM-SQUAREx3-2-70D-/370764126470?pt=LH_DefaultDomain_0&hash=item5653439906

if as a previous post suggested, you use a beveled washer on the bottom/inside the chassis, flat washer on top of the chassis, that pretty much isolates the transformer from the chassis. Once you tighten the nut, the beveled washer gets squeezed up through the chassis hole and makes contact with the top washer. I would also use a washer under the beveled washer so that the nut does not damage it.

I ended up using flat as well as bevelled washers for the transformer on my custom SP9, it seems to work really well, the screws nor the transformer are making any contact with the chassis.I also used s/steel washers under the bevelled washer so that the nut would not bite into the rubber.

Luddite wrote:Just for the record, I've found that audible noise from power transformers was most often conducted through the chassis to the shelf. The shelf acts like a sound board and increases the audibility of the noise. Vibrapods or some other type of Sorbothene feet should resolve this problem. If you want to experiment before buying these, get several (cheap) art gum erasers from a school or art supply store and rest the chassis on three or four of these. Heck, you might even decide to just keep the erasers and spend your serious money elsewhere.